Convection-enhanced
delivery (CED) of manganese(III)-transferrin (Mn(III)-Tf) into the rat brain
was used to investigate its properties as an in vivo MRI contrast agent.The spatio-temporal evolution of MEMRI
signal enhancement and calculated T1 relaxation times following Mn(III)-Tf
infusion was comparable to that observed following CED of Mn2+ alone.Furthermore, Mn2+ released following
intrastriatal Mn(III)-Tf infusion was transported along the striatonigral
pathway and the temporal dynamics were in excellent agreement with the
neuronal tract tracing studies that employ Mn2+ alone.The results of this study are consistent
with the release and subsequent transport of Mn2+ following receptor-mediated
endocytosis of Mn(III)-Tf.